Ann Romney is set to appear at a GOP rally Thursday at Marquette University. Doors open at 9:30 a.m. The event is slated to begin two hours later.

The visit underscores again how Wisconsin has become a key battleground state in the November election. Her husband's running mate, U.S. Rep. Paul Ryan, hails from Janesville and held a campaign event near Green Bay last week. Vice President Joe Biden has visited the state twice in the last month.